Ventilation

While heat in the boat isn’t strictly a galley issue, cooking is the one thing that puts the most heat into the boat. Different cruisers cope in different ways:

Some stay in marinas where they can run air conditioning.

Some opt for being part-year cruisers, either returning to a second home or making extended visits to family and friends.

Others cope by more or less refusing to cook in the galley, instead using the grill for almost everything.

We opted for a fourth choice: improving our boat’s ventilation so that the cooking heat didn’t stay in the boat. We wanted to be out in the islands, not at a marina or in the US—the summer is gorgeous in the Sea of Cortez and the water is clearest for snorkeling when the temperatures are the hottest. And while we used the grill somewhat, and I tended to cook on the stove instead of in the oven (although I still baked bread frequently), we didn’t want to totally change our lifestyle.

With a little work and a few hundred dollars in supplies (less than the cost of one month in a slip or airfare back to the US), we dramatically improved the ventilation on the boat without significantly increasing the electrical load. Summers were enjoyable. And when other cruisers came aboard Que Tal, most remarked about how much cooler our boat was than theirs.

Here are our five keys to improving our boat’s ventilation:

First, two things that are totally free—

Remove the screens when there are no bugs.

In the Sea of Cortez, there were rarely bugs to the point where we felt the need for screens. And when the breeze is light, screens block a lot of air movement. When there aren’t a lot of bugs around, try taking your screens out and see how much more air comes in the boat. If needed, replace the screens near sunset or whenever bugs come out where you are. Along the same lines, don’t use no-see-um screens if regular ones will do: no-see-um screens almost totally block any wind.

Open up the cockpit as much as possible.

Screens or side-curtain sunshades enclosing the cockpit also restrict air movement—both in the cockpit and for air to move up and out through the companionway. When we had our dodger and bimini redesigned, Danny from Pacific Thread in La Paz suggested that we make the “windshield” removable—another huge improvement to air flow. Admittedly, if bugs are a big problem where you’re cruising, removing cockpit screens might not be practical, or you might have to put them back in place for part of the day.

And now three more suggestions for improved ventilation, all of which don’t qualify as “cheap”—but all of which we felt all were well worth the money:

Low-draw 12-volt fans

We had 8 fans on board: 1 in the galley, 2 in the saloon, 1 in the head, 2 in the v-berth, 1 in the quarter berth (almost never used) and 1 in the lazarette (not often used, but very appreciated when it was).

We’d only turn on the one(s) where we actually were at any time, and since our preferred Caframo fans only drew 0.6 amps, they were not a significant drain on our batteries. The two in the saloon were not permanently mounted, so we also could move them to the cockpit when needed (see photo at the top of this article!).

The previous owner had installed some of the fans and we added more. We found that we greatly preferred the Caframo 12-volt 2-speed fans to the Hella fans—they moved far more air per amp.

I’ve written a separate article on 12-volt fans, and why we liked these better than other models. However, if you want to go straight to our preferred fans, here’s the link to them:

A wind scoop—or two, depending on your boat’s configuration—brings even the slightest breeze into your boat. I’ve now written an entire article on wind scoops—please read this update with comments on the best designs and a good place to get them.

Exhaust fan in the galley

Cooking heat rises in the galley, so if you can remove some of that heat with an exhaust fan or hatch right over the center of the galley, it will help with the heat in the galley. Now, Dave thought that the exhaust fan didn’t do much for heat in the rest of the boat, but I certainly thought it improved the galley, particularly while I was cooking.

There are two types of exhaust fans: solar powered and hard-wired. We opted for solar powered because it would have been hard to run wires where we needed them and also because we didn’t want to add to the load on the house batteries. However, hard wired from the house batteries generally can move more air.

We removed a passive ventilation dorade box and and installed an exhaust fan in its place. The first fan we got was a 3″ diameter model, as it fit exactly in the hole. When it died, we replaced it with a 4″ fan which moved considerably more air.

As every boat is different in its configuration, it’s hard for me to make specific recommendations. However, a few considerations include:

The larger the diameter of the fan blades, the more air the fan will move.

Make sure it can be set to exhaust!

Think about the type of weather you’re likely to encounter and make sure that the mounting system will be adequate. We bought one fan that was labeled marine, but the mounting system was clearly inadequate—we made it work for coastal cruising, but I wouldn’t have taken it across an ocean. It’s no longer available, but I put the link above where you can read my entire review and see what all the problems were.

Make sure there is a way to solidly seal off the opening if you get into rough seas or nasty storm—how “bulletproof” it has to be depends a lot on where you are—for example, if you’re in hurricane-prone areas you need a much beefier system than if you’re at a marina on Kentucky Lake.

If you want the fan to run all the time, solar is a good way to go for power. If you’re just going to run it when you’re cooking, and you have wiring that’s accessible, I’d opt for a 12-volt fan.

One friend went so far as to purchase a small hatch and install it over the galley area. As it was right at the highest point of the galley and directly over the stove, he didn’t feel that he needed an exhaust fan— the heat just naturally flowed up and out.

Conclusion

No two ways about it, summer in the tropics can be hot. Dave and I, coming from the Midwest, were somewhat more acclimated to it than cruisers coming from the much cooler Pacific coast.

Still, the key for us was planning and preparing in the cooler season for the summer. Having fans and a good wind scoop ready to go can dramatically improve the conditions on your boat and particularly in the galley. And in many places, such as for us in the Sea of Cortez, summer was a wonderful time to be cruising, with the clearest water for snorkeling and generally very calm seas. I would have hated to miss it!

Reader Interactions

Comments

I am installing the square 12V brushless fans used in tower computers. They are designed to run for long periods, move a reasonable amount of air, and are inexpensively purchased almost anywhere (here in the Philippines I paid about $2 per unit. They are designed to plug together so you can mount them singly, in pairs, or in quad arrays for bigger jobs. A simple bracket designed to allow the fan tobe pointed with two degrees of freedom is not hard to make.

I asked Bruce for some more info on these, since the only computer fans I’d seen people using when we were cruising were about 3″ diameter and didn’t move much air (they worked well to ventilate stuffy lockers and so forth, though). I also asked him about radio interference, since these were brushless (hoping there might be less).

He replied that these fans were about 5″ diameter and had been highly recommended by a guy with 40 years’ experience living aboard. Bruce didn’t know about the electrical interference, as he doesn’t have an SSB.

We recently removed an old computer fan (with fan blades) that had been installed in our main berth by the previous owner. Because of it’s square shape and lack of modifications it could only be installed in one spot which wasn’t very effective. We felt it didn’t move much air and it was noisy…plus unsightly. I know aesthetics need to give way to function when you live on a boat but that didn’t stop me hating the way it looked. We have now got an attractive Caframo 12v fan installed which is fantastic, it is multi-directional, has three speed settings and 4 timer options and is much quieter. I now want them all over the boat.

What perfect timing for this article, as we were just talking the other day about purchasing some 12 volt fans for our sailboat! Being new to all of this we were wondering what brands are recommended, and now we know. Thanks so much for all of your helpful information!

We cruise the Gulf coast of Florida and summer is hot. Our boat had a 4 way scoop on board when we bought her and it has been the best ventilation ever. I have since made a second one for another hatch. … Priceless

Oh, never thought of THAT! There are some free-standing scoops that would probably help some . . . I know they don’t trap as much air and you have to turn them as the wind (or tide) changes. Curious if you’ve tried one of those?

In the Summer, I get up early, and do the majority of my cooking for the day (reheats in microwave, later on). Not only does it help, by cooking while it is cooler, but, as the day grows hotter, the less inclined I am to stand at the stove/oven for so long to prepare a meal. Heat can just sap my strength, and having the hard work done, and a nice meal awaiting me, quickly, helps me to eat better meals (instead of something quick and (generally, quite often bad for me). PLUS, if I use paper plates – there is little washing-up, afterwards. If it is soup, stew, or any food that can be contained in a thermos, I “season” a wide-mouth thermos (with hot water), to keep the food hot, until meal time.

I occasionally use a small box fan that fits nicely into the companionway. I close the slider when it is in use. It works like a whole house fan, sucking air through hatches and out tthrough the companionway. It uses some power, but is a great alternative to air conditioning. I leave all the screens in place, so no bugs.

We cruise south Forida as well and at times, even in the winter, it can get stuffy below when the wind dies. I started out with a 110 volt box fan, which moved a lot of air. Problem was the power loss going through an inverter and power consumption rate. The commercially available DC fans just don’t move enough air for us and provide little actual air flow across the body. So, I built my own high capacity DC fans from automobile radiator fans and PWM speed controllers. At 1 to 1.5 amps they provide lots of airflow and are more gentle on the batteries. Components were purchased on EBAY for very little money and I built the rest from scrap wood. We have one in each of the two top hatches.

Another option is PortVisor rain shields, which don’t require a halyard or electricity. They provide cross ventilation, and more importantly, let you keep ports open even when it’s raining. Disclaimer: We are the creator, manufacturer, and seller : Seaworthy Goods..

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Welcome

Hi! I'm Carolyn Shearlock. My husband and I have been cruising over 11 years and 10,000 miles, first on a Tayana 37 monohull and now on a 34' Gemini catamaran. Along the way, we sold pretty much everything we owned (twice!), gained a great boat dog, had a bunch of wonderful times and some adventures . . . and learned a ton about what does and doesn't work!

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